The Boeing Co. on Friday revealed some details of redesigned lithium-ion battery systems for the 787, which has been grounded by authorities for eight weeks since two high-profile, high-temperature failures that severely damaged the batteries and nearby components.During a webcast from Tokyo, where the company earlier briefed officials, executives outlined changes to the batteries and other portions of the system that supplies electrical power to the Dreamliner.Ray Conner, president and CEO of Renton-based Boeing Commercial Airplanes, introduced Mike Sinnett, vice president and chief project engineer for the Everett-based 787 program, who outlined the modifications and made an impassioned case for the company's dedication to safety."It is a safe airplane," Sinnett said. "We have no concerns at all about that."Conner said Boeing hopes it will only be a matter of weeks before 787s can resume service. That, however, will be up to regulators. "It may take longer depending on how the testing goes," Conner said.The improvements include better cell and battery assembly, improved production tests, battery design improvements, charger design improvements and better enclosures for the batteries.The new enclosure, Sinnett said, eliminates the potential for fire because there is very little air inside. And if a battery failure occurs, vapors and odor will be vented overboard.The plane's two lithium-ion batteries provide electrical power on the ground when the two engines and the auxiliary power unit aren't running, as well as some power in flight in the case of engine failure. The batteries are manufactured by Japanese supplier GS Yuasa. The surrounding electrical system is made by Thales Group.Sinnett emphasized during the webcast that the batteries play a limited role, noting they are not "flight-critical." Lithium-ion batteries are not in wide use in aviation, but they are lighter and stronger than comparable power sources. For those and other reasons, Boeing chose lithium ion, he said. But all batteries can have problems, including the more commonly used nickel-cadium type -- thousands of which, Sinnett said, have failed over the years.Boeing 787s have been grounded by the Federal Aviation Administration and regulators in other countries, including Japan, since Jan. 16. Two incidents prompted that:

On Jan. 7, a lithium-ion battery on a Japan Airlines 787 began to burn after the plane arrived in Boston from Japan. Smoke found its way into the cabin after passengers and crew members had disembarked. A few days later, the FAA said it would conduct an extensive review of the design as well as the FAA's earlier approval of it, but the agency and Boeing both declared the 787 electrical system safe.

On Jan. 15 in Japan, a 787 flown by launch customer All Nippon Airways made an emergency landing when a lithium-ion battery failed and crew members detected an odor. Later investigation found the battery showed signs of electrical arcing.

The next day, the FAA grounded 787s in the U.S., saying the two incidents both "resulted in release of flammable electrolytes, heat damage and smoke." Other countries followed suit. In all, there were 49 787s in service worldwide, 24 of them in Japan, at the time of the grounding.In neither incident was major airplane structure damaged, Sinnett said, and there was only minor damage within 20 inches of the batteries. The Boston incident involved small flames, he said, but there were no flames in the battery failure in Japan."This is an important point: There was no fire at all," Sinnett said.The batteries vented electrolyte, which looks like smoke but is not caused by combustion, Sinnett said. "We can say with certainty that after the battery failed the airplane responded exactly as we designed and intended."On Tuesday, the FAA gave Boeing the green light to proceed with the company's plan to prove the battery-system redesign will be a safe solution -- despite the fact neither the company nor government investigators yet know precisely what caused the problems aboard the two jets.When asked how the company can feel confident that the modifications will work, Sinnett said: "We've addressed many possible things," and not just a single known problem.The approval process will include test flights involving two Boeing 787s with new systems installed, as well as laboratory analysis, the FAA said."The FAA will approve the redesign only if the company successfully completes all required tests and analysis to demonstrate the new design complies with FAA requirements," the agency said in a news release.Meanwhile, the National Transportation Safety Board, which has no regulatory authority but plenty of influence, plans to hold a forum about lithium-ion battery technology and, separately, an official hearing into the Boston incident, which it continues to investigate.No dates have been announced for those events, which the NTSB said will occur in April.Boeing has posted on the Web extensive material outlining its commitment to safety and explaining how the company is working with authorities to resolve the battery problems. And you can watch a replay of the webcast here.Said Sinnett: "We understand very deeply that we do not have a business, we do not have an industry, unless it is safe and we advance safety every day."

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